What Are Ground Control Points?

A ground control point is a place that you can identify from aerial photographs. They are often shaped like a checkerboard and are almost always black and white. Surveyors measure these points with traditional methods, LiDAR, an existing map, or Google Earth. In the worst-case scenario, they need to refly the entire site to ensure they have the correct position. Fortunately, the process is easy and can be done by just about anyone, even if you are not an aerial photographer.

You can use GCPs to mark specific locations on a map. Unlike traditional Xs, these points are marked with a distinctive “L” shape. It gives your drone map an even higher global accuracy than ever before. Ground Control Points are more accurate because they are marked by surveyors before the flight. Here’s more information about ground control points. Read on to learn how they work and why they are so important.

Aerial & Drone imagery acquisition have a crystal clear center point.

Traditionally, ground control points are hard to see from aerial photos. They are too small to be visible at high altitudes, which leads to inaccuracy. High-Resolution Aerial Imagery is highly visible in a wide range of environments with high value fit for photogrammetry accuracy.

The ground control point is a simple and effective way to monitor a project. Its 16″x16″ size makes it easy to be seen in aerial photographs, even 400 feet above the ground. The material’s matte finish reduces glare and allows for photogrammetry.

They are surveyed and marked before the flight.

Before the flight, surveyors mark and survey ground control points. These points are identified with a marker that is 3cm in width. It is necessary to select an altitude that will meet this GSD. It can be difficult if there are repetitive features. Markers should be easy to identify on raw images. In some cases, surveyors use reference maps to determine real-world coordinates.

A common mistake that surveyors make is focusing on the quantity and distribution of the ground control points. Depending on the flight altitude and the accuracy required, surveyors set up a minimum of five GCPs per project. However, they tend to overlook the quality of the aerial targets.

GCPs improve the global accuracy of your drone map.

Ground control points improve the global accuracy of your drone map by ensuring latitude and longitude correspond to GPS coordinates. However, they aren’t always accurate enough for these tasks. Fortunately, GCPs can improve the accuracy of your drone maps. Drones are an excellent tool for gathering accurate data and creating 3D maps. Precision mapping is an essential component of virtual design and construction projects.

The amount of ground control points needed varies depending on the terrain and size of your site. Experts recommend using five to ten ground control points. However, in some cases, experts need as many as 20 ground control points to achieve maximum accuracy. It is important to note that more ground control points do not necessarily mean higher accuracy.

Precise mapping

The purpose of ground control points is to increase the global accuracy of aerial mapping maps. These points are not necessary for every survey but are typically used in projects that require precise mapping. These include construction, agricultural surveys, and topographical surveys. The use of GCPs increases survey accuracy and provides a frame of reference for the entire project.

How to make a GCPs

GCPs are typically made of weatherproof materials such as plastic, rubber, or acrylic. Alternatively, they can be made from a number or letter. Either way, they need to have a clear center and a crossover. In some cases, GCPs are painted using a stencil. In most cases, the target must be large enough for visibility from flight altitude. Alternatively, GCPs can be created with non-marking paint or natural features.